Unix Tutorial

Here command is the name of the command you want to execute. The file /dev/null is a special file that
automatically discards all its input.
To discard both output of a command and its error output, use standard redirection to redirect STDERR to
STDOUT:
$ command > /dev/null 2>&1
Here 2 represents STDERR and 1 represents STDOUT. You can display a message on to STDERR by
redirecting STDIN into STDERR as follows:
$ echo message 1>&2
Redirection Commands:
Following is the complete list of commands which you can use for redirection:
Command
pgm > file
pgm < file
pgm >> file
n > file
n >> file
Description
Output of pgm is redirected to file
Program pgm reads its input from file.
Output of pgm is appended to file.
Output from stream with descriptor n redirected to file.
Output from stream with descriptor n appended to file.
n >& m Merge output from stream n with stream m.
n